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This paper proposes a vehicle–pedestrian cellular automata model to investigate the characteristics of the mixed traffic at a single lane roundabout. The roundabout boundary is controlled by the injecting rates α 1 , α 2 and the extracting rate β whereas pedestrians are generated with arrival probability P cr . The pedestrian and vehicle flux are calculated in terms of rates. Also, the phase diagrams of the system in the ( α 1 , P cr ) and ( α 1 , β ) spaces are constructed. The results show that, the gridlock state is reached only when the pedestrians have the right of way over vehicles, while the maximum current state is reached when including a pedestrians’ crossing decision rule. Likewise, we have found that the crosswalk location play a chief role in improving the dynamic characteristics of pedestrian and vehicle flux. Furthermore, it has turned out that the traffic is sensitive to the driver behavior. [ABSTRACT FROM AUTHOR]

Abstract: The effect of a random surface field, within the bimodal distribution, on the layering transitions in a spin- Ising thin film is investigated using Monte Carlo simulations. It is found that the layering transitions depend strongly on the concentration p of the disorder of the surface magnetic field, for a fixed temperature, surface and external magnetic fields. Indeed, the critical concentration at which the magnetisation of each layer k changes the sign discontinuously, decreases with increase in applied surface magnetic field, for fixed values of the temperature T and the external magnetic field H. Moreover, the behaviour of the layer magnetisations as well as the distribution of positive and negative spins in each layer, are also established for specific values of , H, p and temperature T. [Copyright &y& Elsevier]

The effect of the transverse field Ω on bulk melting and layering sublimation transitions of a spin-1 Blume–Emery–Griffiths (BEG) model is studied using the mean field theory. It is found that there exists a critical value of the transverse field Ωl above which a sequence of layering sublimation occurs before melting bulk transition.Ωl depends on the value of temperature T and chemical potential Δ. Indeed, Ωl decreases with increasing temperature and/or decreasing chemical potential. Phase diagrams in the (Ω–T) and (Ω–Δ) planes are established. However, the increase of the transverse field favours the layering sublimation and bulk melting transitions. Moreover, the (Ω–T) phase diagrams show that the sequence of the critical end points go to the roughness transverse field ΩR and the roughness temperature TR which depend on the value of the chemical potential. Hence, ΩR increases and TR decreases when Δ increases. The profiles of densities and magnetizations as a function of the chemical potential, transverse field and the depth of the film are calculated. [Copyright &y& Elsevier]

Abstract The crystal field effect on the layering transitions of the spin-1 Blume–Capel model is studied, in the presence of external and surface magnetic field, using Monte Carlo simulations. The ground state phase diagrams were determined analytically. We showed that existing phases are strongly dependent on the surface and the bulk crystal field. At finite temperature, the phase diagrams have been examined in detail. In particular, different phases are found to be separated for different configurations. To complete this study, we discuss and interpret the behavior of the magnetizations and the quadrupolar moments. Highlights • We have studied the effect of the crystal field on the layering transitions. • Using Monte Carlo simulations, we study this system. • We have elaborated the ground state phase diagrams of the system. • A low temperature values, we have determined the magnetizations. [ABSTRACT FROM AUTHOR]

In this work, we have analyzed the behavior of the 2D Ashkin–Teller model with spin-1 under the effect of the quantum transverse field and longitudinal crystal field. However, using mean field theory, three new diagrams of phase are found by varying the crystal field values. On the other hand, three others new phase diagrams with different quantum transverse field values. Therefore, multicritical behaviors are studied as a function of four-spin interaction coefficient ( J 4 ∕ J 1 ) . Moreover, for the objective of assuring the existence of the different phases in the phase diagrams, we have plotted in addition the variation of the transverse field as a function of crystal field. [ABSTRACT FROM AUTHOR]

In this paper, we investigated a non-signalized T-shaped intersection using the cellular automata model under the open boundary condition. Two different priority rules at intersection are introduced (Rule 1, Rule 2) to eliminate the jam-packed state. Phase diagram and its variation with the ratios of right and/or left turning vehicles are investigated. The space-time and the density profiles are also studied. The simulation results indicate that the system does not show the same performance under different priority rules, where Rule 1 (resp. Rule 2) can be better than Rule 2 (resp. Rule 1) according to the ratios of turning vehicles. [ABSTRACT FROM AUTHOR]

In this paper we study, using mean field theory (MFT), the effect of the anisotropic Dzyaloshinskii–Moriya (DM) interaction on the phase diagrams of the spin-half Ashkin–Teller model on hypercubic lattice. Different new phase diagrams are found by varying the anisotropy of DM interaction. The multicritical behavior is studied as a function of four-spin interaction coefficient J 4 / J 1 and for two fixed values of spin interaction coefficient J 2 / J 1 . [ABSTRACT FROM AUTHOR]

Traffic flow behavior and velocity correlation in a bidirectional two lanes road are studied using Cellular Automata (CA) model within a mixture of fast and slow vehicles. The behaviors of the Inter-lane and Intra-lane Velocity Correlation Coefficients (V.C.C.) due to the interactions between vehicles in the same lane and the opposite lane as a function of the density are investigated. It is shown that high densities in one lane lead to large cluster in the second one, which decreases the Intra-lane velocity correlations and thereby form clusters in the opposite lane. Moreover, we have found that there is a critical density over which the Inter-lane V.C.C. occurs, but below which no Inter-lane V.C.C. happens. The spatiotemporal diagrams correspond to those regions are derived numerically. Furthermore, the effect of the overtaking probability in one lane on the Intra-lane V.C.C. in the other lane is also investigated. It is shown that the decrease of the overtaking probability in one lane decreases slightly the Intra-lane V.C.C. at intermediate density regimes in the other lane, which improves the current, as well as the Inter-lane V.C.C. decreases. [ABSTRACT FROM AUTHOR]

In this paper, we propose a two-lane cellular automata model that explains the relationship between traffic-related parameters and likelihood of accidents P a c at a signalized intersection. It is found that, the risk of collision rises as well as the lane-changing probability P c h g augments, besides, the accidents and inflow α show a nonlinear relationship. Moreover, P a c exhibits three different phases (I, II and III) depending on α. Likewise, the system exhibits a second (first) order transition from phase I to phase II when P c h g >0 ( P c h g = 0). Nevertheless, the transition from phase II to phase III is of first (second) order when P c h g > 0 ( P c h g = 0). In addition, the result analysis shows that the distribution of accidents according to the intersection sites is not equiprobable. Furthermore, when the traffic arriving strength is not very high, the green light length of one road should be increased to restrain P a c and enhance the road safety. Finally, the model results illustrated that the traffic at the intersection is more dangerous adopting asymmetric lane-changing rules than symmetric ones. • We investigated the risk of accidents at a signalized intersection using CA model. • Lane-changing probability has a significant effect on the risk of accidents. • The probability of accidents exhibits three phases depending on the injection rate. • Over 50% of all accidents occur at the fourth site of the intersection. • Traffic intersection is more dangerous adopting asymmetric rules than symmetric ones. [ABSTRACT FROM AUTHOR]

Using Monte Carlo simulations, we studied the effect of uniform external longitudinal magnetic field on the 3 d isotropic Heisenberg disordered model. Simulations are performed for a variety of fields. Our results confirm that the mixed chiral phase must belong to the same class of universality with those of zero fields and with same group of critical exponent. • Monte Carlo study of the effect of the magnetic field on the 3d disordered isotropic Heisenberg model. • The Binder cumulant is used to determine the critical temperature. • The finite size scaling theory is used to determine the critical exponents. • Other field values are also studied. • The mixed chiral phase is found, and belong to the same class of universality with those of zero fields and with the same group of critical exponents. [ABSTRACT FROM AUTHOR]

The half-metallic ferromagnetic of Gallium nitride doped with double impuritiesGa 1 − 2 x Mn x Co x N ( x = 3 % and 6%) has been investigated by means of first principles investigation combined with Monte Carlo Simulation. The stability of the ferromagnetic state is investigated by comparing the total energies to the spin-glass state. The exchange interactions obtained from first principle calculations and used in a classical Ising model by a Monte Carlo approach resulted in half-metallic ferromagnetic states with high Neel temperature. [ABSTRACT FROM AUTHOR]

Despite the extensive research on traffic dynamics and epidemic spreading, the effect of the routing algorithms strategies on the traffic-driven epidemic spreading has not received an adequate attention. It is well known that more performant routing algorithm strategies are used to overcome the congestion problem. However, our main result shows unexpectedly that these algorithms favor the virus spreading more than the case where the shortest path based algorithm is used. In this work, we studied the virus spreading in a complex network using the efficient path and the global dynamic routing algorithms as compared to shortest path strategy. Some previous studies have tried to modify the routing rules to limit the virus spreading, but at the expense of reducing the traffic transport efficiency. This work proposed a solution to overcome this drawback by using a selective vaccination procedure instead of a random vaccination used often in the literature. We found that the selective vaccination succeeded in eradicating the virus better than a pure random intervention for the performant routing algorithm strategies. [ABSTRACT FROM AUTHOR]

Two nonperturbative methods such as Monte-Carlo simulation (MC) and Transfer-Matrix Finite-Size-Scaling calculations (TMFSS) have been used to study the phase transition of the spin- 3 / 2 ​Blume–Emery–Griffiths model (BEG) with quadrupolar and antiferromagnetic next-nearest-neighbor exchange interactions. Ground state and finite temperature phase diagrams are obtained by means of these two methods. New degenerate phases are found and only second order phase transitions occur for all values of the parameter interactions. No sign of the intermediate phase is found from both methods. Critical exponents are also obtained from TMFSS calculations. Ising criticality and nonuniversal behaviors are observed depending on the strength of the second neighbor interaction. [ABSTRACT FROM AUTHOR]

Abstract: On the basis of ab initio calculations (FPLO) and Monte Carlo Simulations (MCS) the phase diagrams and magnetic properties of the bulk perovskite LaMnO3 have been studied, using the Heisenberg model. It is shown, using ab initio calculations in the scalar relativistic scheme, that the stable phase is the antiferromagnetic A-type, which corresponds to ferromagnetic order of the manganese ions in the basal planes and antiferromagnetic order of these ions between these planes along the axis. Using the full four-component relativistic scheme, in order to calculate the magnetic anisotropy energy and constants, it is found that the favorable magnetic direction is the (010) axis. The transition temperatures and the critical exponents are obtained in the framework of Monte Carlo simulations. The magnetic anisotropy and the exchange couplings of the Heisenberg model are deduced from ab initio calculations. They lead, by using Monte Carlo simulations, to a quantitative agreement with the experimental transition temperatures. [Copyright &y& Elsevier]

We use a cellular automata approach to describe the interactions of the immune system with the human immunodeficiency virus (HIV). We study the evolution of HIV infection, particularly in the clinical latency period. The results we have obtained show the existence of four different behaviours in the plane of death rate of virus–death rate of infected T cell. These regions meet at a critical point, where the virus density and the infected T cell density remain invariant during the evolution of disease. We have introduced two kinds of treatments, the protease inhibitors and the RT inhibitors, in order to study their effects on the evolution of HIV infection. These treatments are powerful in decreasing the density of the virus in the blood and the delay of the AIDS onset. [Copyright &y& Elsevier]

Although extensive research has been devoted to treat virus propagation over decades, the effect of local routing protocols algorithms on it has been ignored. In this paper, we studied the effectiveness of local routing protocols and their additional algorithms; next-nearest neighbors (NNN) and restrictive queue- length algorithm (RQL) in term of robustness in computer virus spreading. It is found that, the local routing protocols without additional algorithms favor the virus spreading, due to the blind transmission of packets between source and destination, while in local routing protocols under (NNN) algorithm, the virus propagation is reduced remarkably. Moreover in local routing protocols under RQL, the virus propagation continues to be reduced more and more compared with NNN algorithm. Furthermore our results show that the node duplication avoidance (NDA) algorithm favors the computer virus spreading especially in sparse networks. Moreover, in comparison with shortest path (SP) and efficient path (EP) global routing strategies ,local routing protocols under the restrictive queue- length algorithm (RQL), the virus propagation is highly reduced and becomes unexpectedly comparable to the traditional shortest path strategy and overcomes the efficient path strategy which shows a high vulnerability and sensitivity to computer virus propagation. These results could be very helpful for network routing protocols designers to give more attention to local routing strategies and their additional algorithms in order to benefit from high capacity and high level of security plus the adaptability with the large scale free networks as the internet. [ABSTRACT FROM AUTHOR]